Gate on array circuit and liquid crystal display

ABSTRACT

The present disclosure proposes a gate on array (GOA) circuit and a liquid crystal display. The stage GOA unit circuit at each stage includes a stage transmission signal enhancement module. The stage transmission signal enhancement module includes comprises a first input terminal fed with the first constant voltage, a second input terminal fed with the second constant voltage, and an output terminal electrically connected to the input terminal of the stage transmission signal output module. The stage transmission signal enhancement module is used to to output a first constant voltage or a second constant voltage to an input terminal of the stage transmission signal output module, according to the stage transmission signal by the previous stage GOA unit circuit.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The current invention relates to liquid crystal display (LCD)technology, and more specifically, to a gate on array (GOA) circuit andLCD.

2. Description of the Prior Art

A GOA circuit makes use of the existing thin-film transistor liquidcrystal display (TFT-LCD) array process to form a gate driver on a GOAsubstrate to realize a driving method of progressive scan. Comparingwith traditional chip on film (COF) or chip on glass (COG) technology,GOA technology saves production cost and can skip the gate directionbonding step. It is extremely beneficial to increase production capacityand elevate the integration of the display facility.

Currently, most GOA circuit uses stage transmission signals to directlyturn on the next stage GOA circuit. However, given that the stagetransmission signal is attached with larger loading, delays occur quiteoften when there's characteristic deviation in the technology or device.Through stage transmission, these delays of stage transmission signalswill be passed down stage by stage, thus affect the operation of thenext stage GOA circuit, and the influence of the delays increases duringthe process of transmission.

SUMMARY OF THE INVENTION

The present invention provides a GOA circuit that can effectively solvedelays that often occur because of higher loading carried by the stagetransmission signal with the existing technology, therefore eliminatethe technical problem of an increased influence of delays during theprocess of stage transmission.

In one aspect of the present invention, a gate on array (GOA) circuitcomprises a plurality of stages of GOA unit circuits connected incascade. The GOA unit circuit at each stage comprises: a forward andbackward scanning control module to transmit the stage transmissionsignal of a previous stage GOA unit circuit to the stage transmissionsignal enhancement module; a stage transmission signal enhancementmodule to be controlled by the stage transmission signal by the previousstage GOA unit circuit to output a first constant voltage or a secondconstant voltage to an input terminal of the stage transmission signaloutput module. The first constant voltage is a constant low voltage, andthe second constant voltage is a constant high voltage. A voltage levelof the second constant voltage is smaller than that of the firstconstant voltage. The forward and backward scanning control modulecomprises an input terminal electrically connected to an output terminalof the previous stage GOA unit circuit, and an output terminalelectrically connected to a control terminal of the stage transmissionsignal enhancement module. The stage transmission signal enhancementmodule comprises a first input terminal fed with the first constantvoltage, a second input terminal fed with the second constant voltage,and an output terminal electrically connected to the input terminal ofthe stage transmission signal output module.

In at least one embodiment, the stage transmission signal enhancementmodule comprises: a first thin-film transistor (TFT), comprising a gateelectrically connected to the output terminal of the forward andbackward scanning control module, and a source fed with the firstconstant voltage; a second TFT, comprising a gate and source fed withthe second constant voltage, and a drain electrically connected to thedrain of the first TFT; a third TFT, comprising a gate electricallyconnected to the drain of the second TFT, and a source fed with thefirst constant voltage; and a fourth TFT, comprising a gate electricallyconnected to the gate of the first TFT, a source fed with the secondconstant voltage, and a drain electrically connected to the inputterminal of the stage transmission signal output module and the drain ofthe third TFT.

In at least one embodiment, the first TFT, second TFT, third TFT andfourth TFT are N-type TFTs.

In at least one embodiment, the forward and backward scanning controlmodule comprises: a fifth TFT, comprising a source fed with a stagetransmission signal of the (N−1)th stage GOA unit circuit, a gate fedwith a forward scan signal, and a drain connected to the gates of thefirst and fourth TFTs; and a sixth TFT, comprising a source fed with thestage transmission signal of the (N+1)th GOA unit circuit, a gate fedwith a backward scan signal, and a drain connected to the gates of thefirst and fourth TFTs.

In at least one embodiment, the source of the fifth TFT feeds with astart signal of the circuit in the first stage GOA unit circuit.

In at least one embodiment, the source of the sixth TFT feeds with thestart signal of the circuit in the last stage GOA unit circuit.

In another aspect of the present invention, a gate on array (GOA)circuit comprises a plurality of stages of GOA unit circuits connectedin cascade. The GOA unit circuit at each stage comprises: a forward andbackward scanning control module to transmit the stage transmissionsignal of a previous stage GOA unit circuit to the stage transmissionsignal enhancement module; a stage transmission signal enhancementmodule to be controlled by the stage transmission signal by the previousstage GOA unit circuit to output a first constant voltage or a secondconstant voltage to an input terminal of the stage transmission signaloutput module. The forward and backward scanning control modulecomprises an input terminal electrically connected to an output terminalof the previous stage GOA unit circuit, and an output terminalelectrically connected to a control terminal of the stage transmissionsignal enhancement module. The stage transmission signal enhancementmodule comprises a first input terminal fed with the first constantvoltage, a second input terminal fed with the second constant voltage,and an output terminal electrically connected to the input terminal ofthe stage transmission signal output module.

In at least one embodiment, the first constant voltage is a constant lowvoltage, and the second constant voltage is a constant high voltage.

In at least one embodiment, a voltage level of the second constantvoltage is smaller than that of the first constant voltage.

In at least one embodiment, the stage transmission signal enhancementmodule comprises: a first thin-film transistor (TFT), comprising a gateelectrically connected to the output terminal of the forward andbackward scanning control module, and a source fed with the firstconstant voltage; a second TFT, comprising a gate and source fed withthe second constant voltage, and a drain electrically connected to thedrain of the first TFT; a third TFT, comprising a gate electricallyconnected to the drain of the second TFT, and a source fed with thefirst constant voltage; and a fourth TFT, comprising a gate electricallyconnected to the gate of the first TFT, a source fed with the secondconstant voltage, and a drain electrically connected to the inputterminal of the stage transmission signal output module and the drain ofthe third TFT.

In at least one embodiment, the first TFT, second TFT, third TFT andfourth TFT are N-type TFTs.

In at least one embodiment, the forward and backward scanning controlmodule comprises: a fifth TFT, comprising a source fed with a stagetransmission signal of the (N−1)th stage GOA unit circuit, a gate fedwith a forward scan signal, and a drain connected to the gates of thefirst and fourth TFTs; and a sixth TFT, comprising a source fed with thestage transmission signal of the (N+1)th GOA unit circuit, a gate fedwith a backward scan signal, and a drain connected to the gates of thefirst and fourth TFTs.

In at least one embodiment, the source of the fifth TFT feeds with astart signal of the circuit in the first stage GOA unit circuit.

In at least one embodiment, the source of the sixth TFT feeds with thestart signal of the circuit in the last stage GOA unit circuit.

In at least one embodiment, the stage transmission signal output modulecomprises an output unit, an output pull-down unit, a node input unit, anode control unit, a voltage stabilizer unit and a first capacitor. Theoutput unit comprises: a ninth TFT, comprising a gate electricallyconnected to the first node, a source fed with a second clock signal,and a drain electrically connected to the output terminal of the Nthstage GOA unit circuit; and a second capacitor electrically connected tothe first node and the output terminal of the Nth stage GOA unitcircuit. The voltage stabilizer unit comprises an eighth TFT, a gate fedwith the second constant voltage, a source electrically connected to athird node and a drain electrically connected to the first node. Theoutput pull-down unit comprises a fourteenth TFT, a gate electricallyconnected to the second node, a source fed with the first constantvoltage, and a drain electrically connected to the output terminal ofthe Nth stage GOA unit circuit. The node input unit comprises: a seventhTFT, comprising a gate fed with the first clock signal, a sourceelectrically connected to the drains of the third and fourth TFTs, and adrain electrically connected to the third node; a twelfth TFT,comprising a gate electrically connected to the third node, a source fedwith the first clock signal, and a drain electrically connected to thesecond node; a thirteenth TFT, comprising a gate fed with the firstclock signal, a source fed with the second constant voltage, a drainelectrically connected to the second node. The node control unitcomprises: a tenth TFT, comprising a gate fed with the second clocksignal, and a drain electrically connected to the third node; and aneleventh TFT, comprising a gate electrically connected to the secondnode, a source fed with the first constant voltage, and a drainelectrically connected to the source of the tenth TFT.

In still another aspect of the present invention, a liquid crystaldisplay comprises a gate on array (GOA) circuit. The GOA circuitcomprises a plurality of stages of GOA unit circuits connected incascade. The GOA unit circuit at each stage comprises: a forward andbackward scanning control module to transmit the stage transmissionsignal of a previous stage GOA unit circuit to the stage transmissionsignal enhancement module; a stage transmission signal enhancementmodule to be controlled by the stage transmission signal by the previousstage GOA unit circuit to output a first constant voltage or a secondconstant voltage to an input terminal of the stage transmission signaloutput module. The forward and backward scanning control modulecomprises an input terminal electrically connected to an output terminalof the previous stage GOA unit circuit, and an output terminalelectrically connected to a control terminal of the stage transmissionsignal enhancement module. The stage transmission signal enhancementmodule comprises a first input terminal fed with the first constantvoltage, a second input terminal fed with the second constant voltage,and an output terminal electrically connected to the input terminal ofthe stage transmission signal output module.

In at least one embodiment, the first constant voltage is a constant lowvoltage, and the second constant voltage is a constant high voltage.

In at least one embodiment, a voltage level of the second constantvoltage is smaller than that of the first constant voltage.

In at least one embodiment, the stage transmission signal enhancementmodule comprises: a first thin-film transistor (TFT), comprising a gateelectrically connected to the output terminal of the forward andbackward scanning control module, and a source fed with the firstconstant voltage; a second TFT, comprising a gate and source fed withthe second constant voltage, and a drain electrically connected to thedrain of the first TFT; a third TFT, comprising a gate electricallyconnected to the drain of the second TFT, and a source fed with thefirst constant voltage; and a fourth TFT, comprising a gate electricallyconnected to the gate of the first TFT, a source fed with the secondconstant voltage, and a drain electrically connected to the inputterminal of the stage transmission signal output module and the drain ofthe third TFT.

In at least one embodiment, the first TFT, second TFT, third TFT andfourth TFT are N-type TFTs.

The GOA circuit and the LCD of the present invention add a stagetransmission signal enhancement module between the forward and backwardscanning control module and the stage transmission signal output module,so that the delays will be lowered when the stage transmission signalspass through the stage transmission signal enhancement module. Thedriving ability will also be elevated, so that the influence of delaysof the stage transmission signal on the next stage GOA circuit iseffectively lowered.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a circuit diagram of an Nth stage GOA unit circuit of a GOAcircuit of the present invention.

FIG. 2 is a circuit diagram of a first stage GOA unit circuit of a GOAcircuit of the present invention.

FIG. 3 is a circuit diagram of the last stage GOA unit circuit of a GOAcircuit of the present invention.

FIG. 4 shows waveforms of input signals and key nodes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

These and other objectives of the claimed invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

Please refer to FIG. 1. FIG. 1 is a circuit diagram of the Nth stage GOAunit circuit of a GOA circuit of the present invention.

The GOA circuit of the present invention comprises a plurality of stagesof GOA unit circuits connected in cascade. The GOA unit circuit at eachstage comprises a forward and backward scanning control module 100,stage transmission signal enhancement module 200 and stage transmissionsignal output module 300.

Except the first stage GOA unit circuit and the last stage GOA unitcircuit, the Nth (N being an integer) stage GOA unit circuit comprises:

a forward and backward scanning control module 100, comprising an inputterminal electrically connected to an output terminal of the previousstage GOA unit circuit; and an output terminal electrically connected toa control terminal of the stage transmission signal enhancement module,so to transmit a stage transmission signal from the previous stage GOAunit circuit to the stage transmission signal enhancement module 200.

The stage transmission signal enhancement module 200 comprises a firstinput terminal fed with a first constant voltage, a second inputterminal fed with a second constant voltage, and an output terminalelectrically connected to an input terminal of a stage transmissionsignal output module 300, so to be controlled by the stage transmissionsignal of the previous stage GOA unit circuit to output the first or thesecond constant voltage to an input terminal of the stage transmissionsignal output module 300.

The first constant voltage is a constant low voltage VGL. The secondconstant voltage is a constant high voltage VGH.

A voltage level of the second constant voltage is smaller than that ofthe first constant voltage.

The stage transmission signal enhancement module 200 comprises a firstTFT T1, a second TFT T2, a third TFT T3, and a fourth TFT T4.

The first TFT T1 comprises a gate electrically connected to the outputterminal of the forward and backward scanning control module 100, asource fed with the first constant voltage, and a drain electricallyconnected to a drain of the second TFT T2.

The second TFT T2 comprises a gate and a source fed with the secondconstant voltage.

The third TFT T3 comprises a gate electrically connected to the drain ofthe second TFT T2, a source fed with the first constant voltage, and adrain electrically connected to a drain of the fourth TFT T4.

The fourth TFT T4 comprises a gate electrically connected to the gate ofthe first TFT T1, a source fed with the second constant voltage, and adrain electrically connected to the input terminal of the stagetransmission signal output module 300.

The first TFT T1, second TFT T2, third TFT T3 and fourth TFT T4 areN-type TFTs.

The forward and backward scanning control module comprises a fifth TFTT5 and a sixth TFT T6.

The fifth TFT T5 comprises a source fed with a stage transmission signalof a (N−1)th stage GOA unit, a gate fed with a forward scanning signalU2D, a drain connected to the gates of the first TFT T1 and fourth TFTT4.

The sixth TFT T6 comprises a source fed with a stage transmission signalof a (N+1)th stage GOA unit, a gate fed with a backward scanning signalD2U, a drain connected to the gates of the first TFT T1 and fourth TFTT4.

Alternatively, when the fifth TFT T5 and the sixth TFT T6 are N-typeTFTs, during a forward scan, the forward scanning signal U2D is at ahigh voltage level and the backward scanning signal D2U is at a lowvoltage level; during a backward scan, the forward scanning signal U2Dis at the low voltage level and the backward scanning signal D2U is atthe high voltage level.

Alternatively, when the fifth TFT T5 and the sixth TFT T6 are P-typeTFTs, during a forward scan, the forward scanning signal U2D is at a lowvoltage level and the backward scanning signal D2U is at a high voltagelevel; during a backward scan, the forward scanning signal U2D is at thehigh voltage level and the backward scanning signal D2U is at the lowvoltage level.

The stage transmission signal output module 300 comprises an output unit301, an output pull-down unit 302, and a node input unit 303, a nodecontrol unit 304, a voltage stabilizer unit 305 and a first capacitorC1.

The output unit 301 comprises a ninth TFT T9, comprising a gateelectrically connected to a first node Q(n), a source fed with a secondclock signal CK2, a drain electrically connected to the output terminalof the Nth stage GOA unit circuit, and a second capacitor C2, with oneend electrically connected to the first node Q(n) and another endelectrically connected to the output terminal G(n) of the Nth stage GOAunit circuit.

The voltage stabilizer unit 305 comprises an eighth TFT T8, comprising agate fed with the second constant voltage, a source electricallyconnected to a third node A(n), and a drain electrically connected tothe first node Q(n).

The output pull-down unit 302 comprises a fourteenth TFT T14, comprisinga gate electrically connected to a second node P(n), a source fed withthe first constant voltage, a drain electrically connected to the outputterminal G(n) of the Nth stage GOA unit circuit.

The node input unit comprises a seventh TFT T7, a twelfth TFT T12 and athirteenth TFT T13. The seventh TFT T7 comprises a source electricallyconnected to the drain of the third TFT T3 and the drain of the fourthTFT T4; a gate, along with the source of the twelfth TFT 12 and the gateof the thirteenth TFT T13, fed with the first clock signal CK1; a drain,along with the gate of the twelfth TFT T12, electrically connected tothe third node A(n). The drain of the twelfth TFT T12 and the drain ofthe thirteenth TFT T13 electrically connect to the second node P(n). Thesource of the thirteenth TFT T13 fed with the second constant voltage.

The node control unit 304 comprises a tenth TFT T10 and an eleventh TFTT11. The eleventh TFT T11 comprises a gate electrically connected to thesecond node P(n), a source fed with the first constant voltage, a drainelectrically connected to the source of the tenth TFT T10. The tenthTFT10 comprises a gate fed with the second clock signal CK2, and a drainelectrically connected to the third node A(n).

The first clock signal CK1 and the second clock signal CK2 have oppositephases.

Please refer to FIG. 2 for specifics. In the first stage GOA unitcircuit, the fifth TFT T5 comprises a source fed with a start signal STVof the circuit, a gate fed with the forward scanning signal U2D, and adrain connected to the gate of the TFT T1 and the gate of the fourth TFTT4.

Please refer to FIG. 3. In the last stage GOA unit circuit, the sixthTFT T6 comprises a source fed with the start signal STV of the circuit,a gate fed with the backward scanning signal D2U, and a drain connectedto the gate of the first TFT T1 and the gate of the fourth TFT T4.

Please refer to FIG. 1 and FIG. 4. All TFTs shown in FIG. 1 are N-typeTFTs. The following text describes the operation of a forward scan ofthe GOA circuit of the present invention as an example. The start signalSTV of the circuit triggers the first stage GOA circuit, which drives byscanning stage by stage. When the scanning proceeds to the Nth stage GOAunit circuit, the stage transmission signal G(n−1) of the previousstage, the (N−1)th stage GOA unit circuit, is at a high voltage level.When the forward scanning signal is at the high voltage level and thebackward scanning signal is at a low voltage level, the fifth TFT T5 isturned on and the sixth TFT T6 is turned off, so that the stagetransmission signal G(n−1) is transmitted to the stage transmissionsignal enhancement module.

More specifically, the first TFT T1 and second TFT T2 are turned on atthis moment. The first constant voltage is a constant low voltage, andthe second constant voltage is a constant high voltage. The level of thesecond constant voltage is lower than that of the first constantvoltage, so that a C point is at a low voltage level. Thus, the thirdTFT T3 is turned off and the fourth TFT T4 is turned on, and the outputterminal B of the stage transmission signal enhancement module is pulledup by the second constant voltage to a high voltage level. When thestage transmission signal G(n−1) of the previous stage, the (N−1)thstage GOA unit circuit, is at a low voltage level, the fourth TFT T4 isturned off. However, because the second TFT T2 is influenced by thesecond constant voltage and maintained at a turned-on status, the Cpoint is at a high voltage level, so that the third TFT T3 is turned onand the output terminal B of the stage transmission signal enhancementmodule is pulled down by the first constant voltage to a low voltagelevel.

Through the stage transmission signal enhancement module 200, the stagetransmission signal of the previous stage GOA unit circuit serves as acontrol signal, so to transmit the constant voltage to the stagetransmission signal output module 300 and enhance the signal.

Then, when the first clock signal CK1 is at a high voltage level, thesecond clock signal CK2 is at a low voltage level, the seventh TFT T7and the eighth TFT T8 are turned on and the first node Q(n) is pulled upto a high voltage level, charging the second capacitor C2. When thefirst clock signal CK1 is at the high voltage level and the second clocksignal CK2 is at the low voltage level, the thirteenth TFT T13 and thetwelfth TFT T12 is turned on and the second node P(n) is pulled up to ahigh voltage level. At this moment, the ninth TFT T9 and the fourteenthTFT T14 are turned on, thus the output terminal G(n) of the Nth stageGOA unit circuit is pulled down to a low voltage level.

Then, when the first clock signal CK1 is at a low voltage level, and thesecond clock signal CK2 is at a high voltage level, the seventh TFT T7is turned off and the first node Q(n) maintains at a high voltage levelthrough the capacitor C2, so that the ninth TFT T9 is turned on. Whenthe first clock signal CK1 is at a low voltage level and the secondclock signal CK2 is at a high voltage level, the thirteenth TFT T13 isturned on and the first clock signal CK1 pulls down the P(n), so thatthe fourteenth TFT T14 is turned off. The source of the ninth TFT T9feeds with the second clock signal CK2, thus the output terminal G(n) ofthe Nth stage GOA unit circuit is pulled up to a high voltage level bythe second clock signal CK2.

When the P node is at a high voltage level, and the second clock signalCK2 is at a high voltage level, the eleventh TFT T11 and tenth TFT T10and the eighth TFT T8 are turned on, and the first node Q(n) is pulleddown by the constant low voltage.

The GOA circuit and the LCD of the present invention add a stagetransmission signal enhancement module between the forward and backwardscanning control module and the stage transmission signal output module,so that the delays will be lowered when the stage transmission signalspass through the stage transmission signal enhancement module. Thedriving ability will also be elevated, so that the influence of delaysof the stage transmission signal on the next stage GOA circuit iseffectively lowered.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device may be made while retainingthe teachings of the invention. Accordingly, the above disclosure shouldbe construed as limited only by the metes and bounds of the appendedclaims.

What is claimed is:
 1. A gate on array (GOA) circuit, comprising aplurality of stages of GOA unit circuits connected in cascade, with theGOA unit circuit at each stage comprising: a forward and backwardscanning control module to transmit a stage transmission signal of aprevious stage GOA unit circuit to a stage transmission signalenhancement module; the stage transmission signal enhancement module tobe controlled by the stage transmission signal by the previous stage GOAunit circuit to output a first constant voltage or a second constantvoltage to an input terminal of a stage transmission signal outputmodule; wherein the first constant voltage is a constant low voltage,and the second constant voltage is a constant high voltage, and avoltage level of the second constant voltage is smaller than that of thefirst constant voltage; wherein the forward and backward scanningcontrol module comprises an input terminal electrically connected to anoutput terminal of the previous stage GOA unit circuit, and an outputterminal electrically connected to a control terminal of the stagetransmission signal enhancement module; the stage transmission signalenhancement module comprises a first input terminal fed with the firstconstant voltage, a second input terminal fed with the second constantvoltage, and an output terminal electrically connected to the inputterminal of the stage transmission signal output module, wherein thestage transmission signal enhancement module comprises: a firstthin-film transistor (TFT), comprising a gate electrically connected tothe output terminal of the forward and backward scanning control module,and a source fed with the first constant voltage; a second TFT,comprising a gate and source fed with the second constant voltage, and adrain electrically connected to the drain of the first TFT; a third TFT,comprising a gate electrically connected to the drain of the second TFT,and a source fed with the first constant voltage; and a fourth TFT,comprising a gate electrically connected to the gate of the first TFT, asource fed with the second constant voltage, and a drain electricallyconnected to the input terminal of the stage transmission signal outputmodule and the drain of the third TFT.
 2. The GOA circuit of claim 1,wherein the first TFT, second TFT, third TFT and fourth TFT are N-typeTFTs.
 3. The GOA circuit of claim 2, wherein the forward and backwardscanning control module comprises: a fifth TFT, comprising a source fedwith a stage transmission signal of an (N−1)th stage GOA unit circuit, agate fed with a forward scan signal, and a drain connected to the gatesof the first and fourth TFTs, where N is a positive integer; and a sixthTFT, comprising a source fed with the stage transmission signal of an(N+1)th GOA unit circuit, a gate fed with a backward scan signal, and adrain connected to the gates of the first and fourth TFTs.
 4. The GOAcircuit of claim 3, wherein the source of the fifth TFT feeds with astart signal of the circuit in the first stage GOA unit circuit.
 5. TheGOA circuit of claim 3, wherein the source of the sixth TFT feeds withthe start signal of the circuit in the last stage GOA unit circuit.
 6. Agate on array (GOA) circuit, comprising a plurality of stages of GOAunit circuits connected in cascade, with the GOA unit circuit at eachstage comprising: a forward and backward scanning control module totransmit the stage transmission signal of a previous stage GOA unitcircuit to the stage transmission signal enhancement module; a stagetransmission signal enhancement module to be controlled by the stagetransmission signal by the previous stage GOA unit circuit to output afirst constant voltage or a second constant voltage to an input terminalof a stage transmission signal output module; wherein the forward andbackward scanning control module comprises an input terminalelectrically connected to an output terminal of the previous stage GOAunit circuit, and an output terminal electrically connected to a controlterminal of the stage transmission signal enhancement module; the stagetransmission signal enhancement module comprises a first input terminalfed with the first constant voltage, a second input terminal fed withthe second constant voltage, and an output terminal electricallyconnected to the input terminal of the stage transmission signal outputmodule, wherein the stage transmission signal enhancement modulecomprises: a first thin-film transistor (TFT), comprising a gateelectrically connected to the output terminal of the forward andbackward scanning control module, and a source fed with the firstconstant voltage; a second TFT, comprising a gate and source fed withthe second constant voltage, and a drain electrically connected to thedrain of the first TFT; a third TFT, comprising a gate electricallyconnected to the drain of the second TFT, and a source fed with thefirst constant voltage; and a fourth TFT, comprising a gate electricallyconnected to the gate of the first TFT, a source fed with the secondconstant voltage, and a drain electrically connected to the inputterminal of the stage transmission signal output module and the drain ofthe third TFT.
 7. The GOA circuit of claim 6, wherein the first TFT,second TFT, third TFT and fourth TFT are N-type TFTs.
 8. The GOA circuitof claim 7, wherein the forward and backward scanning control modulecomprises: a fifth TFT, comprising a source fed with a stagetransmission signal of an (N−1)th stage GOA unit circuit, a gate fedwith a forward scan signal, and a drain connected to the gates of thefirst and fourth TFTs, where N is a positive integer; and a sixth TFT,comprising a source fed with the stage transmission signal of an (N+1)thGOA unit circuit, a gate fed with a backward scan signal, and a drainconnected to the gates of the first and fourth TFTs.
 9. The GOA circuitof claim 8, wherein the source of the fifth TFT feeds with a startsignal of the circuit in the first stage GOA unit circuit.
 10. The GOAcircuit of claim 8, wherein the source of the sixth TFT feeds with thestart signal of the circuit in the last stage GOA unit circuit.
 11. TheGOA circuit of claim 9, wherein the stage transmission signal outputmodule comprises an output unit, an output pull-down unit, a node inputunit, a node control unit, a voltage stabilizer unit and a firstcapacitor; the output unit comprises: a ninth TFT, comprising a gateelectrically connected to the first node, a source fed with a secondclock signal, and a drain electrically connected to the output terminalof an Nth stage GOA unit circuit; and a second capacitor electricallyconnected to the first node and the output terminal of the Nth stage GOAunit circuit; the voltage stabilizer unit, comprising an eighth TFT, agate fed with the second constant voltage, a source electricallyconnected to a third node and a drain electrically connected to thefirst node; the output pull-down unit comprises a fourteenth TFT, a gateelectrically connected to a second node, a source fed with the firstconstant voltage, and a drain electrically connected to the outputterminal of the Nth stage GOA unit circuit; the node input unitcomprises: a seventh TFT, comprising a gate fed with the first clocksignal, a source electrically connected to the drains of the third andfourth TFTs, and a drain electrically connected to the third node; atwelfth TFT, comprising a gate electrically connected to the third node,a source fed with the first clock signal, and a drain electricallyconnected to the second node; a thirteenth TFT, comprising a gate fedwith the first clock signal, a source fed with the second constantvoltage, a drain electrically connected to the second node; the nodecontrol unit comprises: a tenth TFT, comprising a gate fed with thesecond clock signal, and a drain electrically connected to the thirdnode; and an eleventh TFT, comprising a gate electrically connected tothe second node, a source fed with the first constant voltage, and adrain electrically connected to the source of the tenth TFT.
 12. Aliquid crystal display, comprising a gate on array (GOA) circuitcomprising a plurality of stages of GOA unit circuits connected incascade, with the GOA unit circuit at each stage comprising: a forwardand backward scanning control module to transmit the stage transmissionsignal of a previous stage GOA unit circuit to the stage transmissionsignal enhancement module; a stage transmission signal enhancementmodule to be controlled by the stage transmission signal by the previousstage GOA unit circuit to output a first constant voltage or a secondconstant voltage to an input terminal of a stage transmission signaloutput module; wherein the forward and backward scanning control modulecomprises an input terminal electrically connected to an output terminalof the previous stage GOA unit circuit, and an output terminalelectrically connected to a control terminal of the stage transmissionsignal enhancement module; the stage transmission signal enhancementmodule comprises a first input terminal fed with the first constantvoltage, a second input terminal fed with the second constant voltage,and an output terminal electrically connected to the input terminal ofthe stage transmission signal output module, wherein the stagetransmission signal enhancement module comprises: a first thin-filmtransistor (TFT), comprising a gate electrically connected to the outputterminal of the forward and backward scanning control module, and asource fed with the first constant voltage; a second TFT, comprising agate and source fed with the second constant voltage, and a drainelectrically connected to the drain of the first TFT; a third TFT,comprising a gate electrically connected to the drain of the second TFT,and a source fed with the first constant voltage; and a fourth TFT,comprising a gate electrically connected to the gate of the first TFT, asource fed with the second constant voltage, and a drain electricallyconnected to the input terminal of the stage transmission signal outputmodule and the drain of the third TFT.
 13. The liquid crystal display ofclaim 12, wherein the first TFT, second TFT, third TFT and fourth TFTare N-type TFTs.